Re: [Xen-devel] [PATCH 2/3] xen-blkfront: rm BUG_ON(info->feature_persistent) in blkif_free

[Bob Liu <bob.liu@xxxxxxxxxx>]

On 07/21/2015 05:25 PM, Roger Pau Monné wrote:
> El 21/07/15 a les 5.30, Bob Liu ha escrit:
>> This BUG_ON() in blkif_free() is incorrect, because indirect page can be 
>> added
>> to list info->indirect_pages in blkif_completion() no matter 
>> feature_persistent
>> is true or false.
>>
>> Signed-off-by: Bob Liu <bob.liu@xxxxxxxxxx>
> 
> Acked-by: Roger Pau Monné <roger.pau@xxxxxxxxxx>
> 
> This was probably an oversight from when blkif_completion was changed to
> check for gnttab_query_foreign_access. It should be backported to stable
> trees.
> 

Sorry, this patch is buggy and I haven't figure out why.

general protection fault: 0000 [#1] SMP 
Modules linked in:
CPU: 0 PID: 39 Comm: xenwatch Tainted: G        W       
4.1.0-rc3-00003-g718cf80-dirty #67
Hardware name: Xen HVM domU, BIOS 4.5.0-rc 11/23/2014
task: ffff880283f4eca0 ti: ffff880283fb4000 task.ti: ffff880283fb4000
RIP: 0010:[<ffffffff813d577b>]  [<ffffffff813d577b>] blkif_free+0x162/0x5a9
RSP: 0018:ffff880283fb7c48  EFLAGS: 00010087
RAX: dead000000200200 RBX: ffff880141400000 RCX: 0000000000000000
RDX: dead000000100100 RSI: dead000000100100 RDI: ffff88028f418bb8
RBP: ffff880283fb7ca8 R08: dead000000200200 R09: 0000000000000001
R10: 0000000000000001 R11: 0000000000000000 R12: ffff8801414481c8
R13: dead0000001000e0 R14: ffff8801414481b8 R15: ffffea0000000000
FS:  0000000000000000(0000) GS:ffff88028f400000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000000001582e08 CR3: 000000013345b000 CR4: 00000000001406f0
Stack:
 ffff880023aa8420 0000000000000286 ffff880283fb7cb7 ffff880023aa8420
 ffff8800363fe240 ffffffff81862c50 ffff880283fb7ce8 ffff880023aa8440
 ffffffff81870000 ffff880023aa8400 ffff880141400000 ffff880141400008
Call Trace:
 [<ffffffff813d8e76>] blkfront_remove+0x4c/0xff
 [<ffffffff813772fa>] xenbus_dev_remove+0x76/0xb0
 [<ffffffff813bd611>] __device_release_driver+0x84/0xf8
 [<ffffffff813bd6a3>] device_release_driver+0x1e/0x2b
 [<ffffffff813bd1ef>] bus_remove_device+0x12c/0x141
 [<ffffffff813ba51d>] device_del+0x161/0x1e5
 [<ffffffff81375ef3>] ? xenbus_thread+0x239/0x239
 [<ffffffff813ba5e4>] device_unregister+0x43/0x4f
 [<ffffffff81377853>] xenbus_dev_changed+0x82/0x17f
 [<ffffffff81377566>] ? xenbus_otherend_changed+0xf0/0xff
 [<ffffffff81378d8d>] frontend_changed+0x43/0x48
 [<ffffffff81375fec>] xenwatch_thread+0xf9/0x127
 [<ffffffff81078fc4>] ? add_wait_queue+0x44/0x44
 [<ffffffff8106195b>] kthread+0xcd/0xd5
 [<ffffffff81060000>] ? alloc_pid+0xe8/0x492
 [<ffffffff8106188e>] ? kthread_freezable_should_stop+0x48/0x48
 [<ffffffff81533ee2>] ret_from_fork+0x42/0x70
 [<ffffffff8106188e>] ? kthread_freezable_should_stop+0x48/0x48
Code: 04 00 4c 8b 28 48 8d 78 e0 49 83 ed 20 eb 3d 48 8b 47 28 48 8b 57 20 48 
be 00 01 10 00 00 00 ad de 49 b8 00 02 20 00 00 00 ad de <48> 89 42 08 48 89 10 
48 89 77 20 4c 89 47 28 31 f6 e8 26 7d cf 
RIP  [<ffffffff813d577b>] blkif_free+0x162/0x5a9
 RSP <ffff880283fb7c48>
---[ end trace 5321d7f1ef8414d0 ]---

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